This study is to determine the feasibility of altering the penetrability of primate cervical mucus (CM) with nonsteroidal agents, both for the purposes of contraception and treatment of infertility. Changes in electrolyte composition during the normal human menstrual cycle are being correlated temporally with levels of steroids and gonadotropins and with CM penetrability. These studies use monkeys and chimpanzees. Hormone RIA is carried out by established procedures. Electrolyte composition is assessed by scanning EM/EDAX, a technique which allows simultaneous analysis of a number of different elements, as well as localization of electrolyte within heterogenous samples. CM penetrability and sperm viability are assessed by a light microscopic procedure which measures rate of transport of sperm through CM. CM properties and electrolyte composition are altered in vitro by dialysis versus inorganic and organic salts. CM is evaluated for: 1) water content and viscosity, 2) appearance of glutaraldehyde-fixed, freeze-dried samples in the light and electron microscopes, with special attention to crystallinity and pore size of the glycoprotein mesh, 3) influence on sperm penetration and viability and 4) elemental composition. These investigations, already under way in continuously estrogen-treated monkeys, will be extended to humans.